I’m so confused

I don’t really understand why it’s such a big deal that Rudieger won’t care that Judith possessed the body of og Judith. Like it’d be one thing if he met and got to know og Judith before this one took over her body, cause it’d be like “I knew both, so who did I really fall in love with?” but the fact that Luca and Judith are acting like not caring about a woman he pretty much never met is somehow proof that it’s dangerous to love him just doesn’t make sense to me. Am I missing something, cause it’s feeling like i must if I don’t get it???